Unalaska is the chief center of population in the Aleutian Islands. The city is in the Aleutians West Census Area, a regional component of the Unorganized Borough in the U.S. state of Alaska. Unalaska is located on Unalaska Island and neighboring Amaknak Island in the Aleutian Islands off mainland Alaska. The population was 4,376 at the 2010 census, which is 79% of the entire Aleutians West Census Area. Unalaska is the second largest city in the Unorganized Borough, behind Bethel.
The Aleut people have lived on Unalaska Island for thousands of years. The Unangan, who were the first to inhabit the island of Unalaska, named it "Ounalashka", meaning "near the peninsula". The regional native corporation has adopted this moniker, and is known as the Ounalashka Corporation. The Russian fur trade reached Unalaska when Stepan Glotov and his crew arrived on August 1, 1759. Natives, Russians and their descendants comprised most of the community's population until the mid-20th century, when the involvement of the United States in World War II led to a large-scale influx of people and construction of buildings all along the strategically located Aleutians.